Cable television systems utilize centralized receiving antennae and transmitting stations in conjunction with networks of cable lines to provide extended television service. However the economics of such systems require a network system that is far too extensive to allow a limited voltage signal to reach the last users on the cables and for this reason signal transmission requires intermittent amplification along the cable. This amplification requires a power input and ordinarily the requisite power is bought from the local utility company, is stepped down and transmitted to a number of amplifiers up and down the cable. However, without special provisions, a system of this configuration produces a cable network that fails for all users beyond any given power failure that affects one set of amplifiers. Such failures create particularly bad customer relations with the subscribers whose home and television set are powered but who are receiving no signal because of a distant power failure.
Various battery operated standby power systems have been developed that both power the amplifiers and continuously charge the standby batteries with power from the utility company's lines and, during power failures, switches to battery power for signal amplification.
Among the important parameters for a standby power system in this environment are the life of the batteries, the duration of standby operation, the wave form generated, the reliability of the system, and the safety precautions to protect the standby power system and associated amplifiers.